Evidence-based·Last reviewed May 31, 2026·How we grade evidence

Chinese Licorice

Botanical

Chinese licorice (Glycyrrhiza uralensis, 'gancao') is one of the most widely used herbs in traditional Chinese medicine — a 'guide herb' added to many formulas. Modern evidence shows modest benefit for canker sores, functional dyspepsia, and post-intubation sore throat. The big problem is glycyrrhizin: even modest regular use raises blood pressure, lowers potassium, and causes edema. The deglycyrrhizinated form (DGL) avoids these risks but loses the antiviral and anti-inflammatory effects.

Quick decision guide

May help most

Adults with recurrent canker sores or mild dyspepsia who choose the deglycyrrhizinated (DGL) form. Whole licorice has a place in TCM-style formulas under a trained practitioner's supervision, with limited duration of use.

Common dosing range

Whole root tea/extract: limit to ≤100 mg glycyrrhizin/day (≈1–2 g dried root) for ≤4 weeks. DGL: 380–1,140 mg chewed before meals.

When to expect effects

Days for canker-sore pain; 2–4 weeks for dyspepsia.

Watch out for

Glycyrrhizin causes pseudohyperaldosteronism — high BP, low potassium, edema. Avoid in pregnancy (preterm birth), heart failure, hypertension, kidney disease, and on diuretics. Many drug interactions.

Evidence snapshot

Canker sores (topical patch)Emerging
Functional dyspepsia (DGL)Emerging
Post-intubation sore throatEmerging
General immune / antiviral useLow

What is it

Chinese licorice (Glycyrrhiza uralensis, Glycyrrhiza inflata) is a traditional Chinese medicine herb whose root contains glycyrrhizin, glycyrrhetinic acid, and many flavonoids (liquiritigenin, isoliquiritigenin, licochalcones).

Is it worth it for you?

Use this as a quick fit check, not a diagnosis.

Worth considering if…

You have recurrent canker sores and want to try a topical licorice patch (modest RCT evidence)
You have mild functional dyspepsia and prefer DGL (deglycyrrhizinated) to avoid systemic effects
You're using it short-term (≤4 weeks) under a TCM practitioner familiar with cumulative-dose risk
You're choosing DGL specifically — it sidesteps the hypertension and potassium risks

Probably skip if…

You have hypertension, heart failure, kidney disease, or are on a diuretic
You're pregnant — preterm birth risk and direct fetal effects documented at higher intakes
You're on warfarin, digoxin, corticosteroids, hormonal contraceptives, or multiple medications — glycyrrhizin alters many drug levels
You eat large amounts of licorice candy regularly — cumulative glycyrrhizin can hit toxic levels
You expect months-long daily use of whole licorice — the dose-time curve for harm is well-described

Evidence at a glance

Aphthous ulcers (canker sores)

Limited Evidence
Effect
Faster pain relief by day 4; smaller lesion size by day 8 vs placebo
Best fit
Adults with recurrent aphthous stomatitis wanting an OTC topical option
Time
Pain relief within days; ulcer healing by ~1 week

Functional dyspepsia (with DGL)

Limited Evidence
Effect
Modest symptom-score reduction at 4 weeks; small-to-moderate effect
Best fit
Adults with mild functional dyspepsia who want a non-PPI option to try first
Time
2–4 weeks

Post-intubation sore throat

Limited Evidence
Effect
Lower incidence and severity of post-operative sore throat
Best fit
Adults undergoing endotracheal intubation
Time
Same-day perioperative effect

Immune / antiviral / general TCM tonic

Mixed Evidence
Effect
No clinical-endpoint evidence as solo therapy
Best fit
None established by Western RCT standards
Time
Not established for these endpoints

Evidence for 4 uses

AI-assisted evidence assessment — talk to your doctor before relying on any single supplement.

Aphthous ulcers (canker sores)

Supplement benefit
Limited Evidence

Martin 2008 randomized 69 adults with active canker sores to glycyrrhiza-extract intraoral adhesive patches, placebo patches, or no treatment. By day 4, 81% of the active group had no pre-stimulus pain vs 63% placebo and 40% no-treatment; by day 8 ulcer size was significantly smaller in the active arm. Topical use bypasses systemic glycyrrhizin absorption almost entirely, so safety is much better than oral whole-root use.

Effect size
Faster pain relief by day 4; smaller lesion size by day 8 vs placebo
Time to effect
Pain relief within days; ulcer healing by ~1 week
Best fit
Adults with recurrent aphthous stomatitis wanting an OTC topical option
Less likely
Major aphthae or Behçet's-related ulcers — need specialist evaluation

Bottom line: A reasonable topical OTC option for canker sores; doesn't carry the BP/potassium risks of oral whole licorice.

SourceMartin et al., 2008 — General Dentistry

Functional dyspepsia (with DGL)

Supplement benefit
Limited Evidence

Several small RCTs of deglycyrrhizinated licorice (DGL) or standardized whole-root extracts (e.g., GutGard) at 75–150 mg/day show reductions in functional-dyspepsia symptom scores over 4 weeks vs placebo. Effect size is modest. DGL has been used historically for ulcer-protective effects, but ulcer-healing trials are inconsistent.

Effect size
Modest symptom-score reduction at 4 weeks; small-to-moderate effect
Time to effect
2–4 weeks
Best fit
Adults with mild functional dyspepsia who want a non-PPI option to try first
Less likely
Active peptic ulcer disease (which needs H. pylori testing + standard therapy), Barrett's, or alarm features

Bottom line: DGL is a reasonable low-risk trial for mild dyspepsia. If symptoms persist or alarm features appear, see your doctor.

SourceMemorial Sloan Kettering Cancer Center — About Herbs — Licorice

Post-intubation sore throat

Disease adjunct
Limited Evidence

Small RCTs of licorice gargle (0.5 g in 30 mL water for 30 seconds) before anesthesia induction reduce post-operative sore throat and cough. NCCIH lists this as one of the indications with modest evidence support.

Effect size
Lower incidence and severity of post-operative sore throat
Time to effect
Same-day perioperative effect
Best fit
Adults undergoing endotracheal intubation
Less likely
Outside the perioperative setting

Bottom line: An anesthesia-team adjunct. Not relevant to outpatient daily supplementation.

SourceNCCIH — Licorice Root: Usefulness and Safety

Immune / antiviral / general TCM tonic

Mechanism only
Mixed Evidence

Glycyrrhizin has antiviral activity in cell-culture and animal models (including against SARS coronaviruses), and Chinese licorice is the most-used 'guide herb' in TCM formulas. In humans, there is no rigorous clinical-trial evidence that licorice alone treats viral illness or general immune dysfunction. Most TCM use is as a small adjunct ingredient in multi-herb formulas, not solo.

Effect size
No clinical-endpoint evidence as solo therapy
Time to effect
Not established for these endpoints
Best fit
None established by Western RCT standards
Less likely
Anyone using it as a standalone antiviral or 'immune support' supplement

Bottom line: Interesting biochemistry, no proven clinical antiviral benefit. Don't take chronic whole licorice for 'immune support' — the BP/potassium risks are real and the upside isn't.

SourceMemorial Sloan Kettering Cancer Center — About Herbs — Licorice

How it works

Glycyrrhizin inhibits 11-beta-hydroxysteroid dehydrogenase type 2, allowing endogenous cortisol to activate mineralocorticoid receptors. This produces sodium retention, potassium loss, and elevated blood pressure with sustained use. Flavonoids contribute antioxidant, antiviral, and anti-inflammatory activity. Deglycyrrhizinated licorice (DGL) preserves the flavonoids and gastric-protective effects while removing glycyrrhizin to avoid hypertension and hypokalemia.

How to take it

1. Typical dose
• DGL (deglycyrrhizinated): 380–1,140 mg chewed 20 min before meals, ≤8 weeks • Whole licorice root tea/extract: limit to ≤100 mg glycyrrhizin/day (~1–2 g dried root) • Topical patch (canker sores): 1 patch over the lesion as directed • Limit duration of any whole-licorice use to ≤4 weeks, with rest periods
2. Higher studied dose
Most short-term trials use 75–150 mg glycyrrhizin-equivalent/day. NCCIH cautions that even 100 mg/day for several weeks can cause hypertension and hypokalemia in susceptible people.
3. Timing
DGL before meals on an empty stomach for dyspepsia. Topical patch as needed during a canker-sore flare.
4. With food
DGL is taken before meals; whole extract can be taken with or without food.
5. Split dosing
Yes — split DGL into 2–3 doses before meals.
6. How long to try
≤4 weeks for whole licorice. ≤8 weeks for DGL. Take treatment breaks of ≥1 month before repeating whole-licorice courses.

What to track

Home blood pressure (twice weekly if on whole licorice)
Ankle swelling / weight gain (signs of fluid retention)
Muscle weakness, cramping, palpitations (signs of hypokalemia)
Headache and lethargy (early pseudoaldosteronism)
Serum potassium if using >2 weeks and you're at risk

Bottom line: If you want licorice's GI benefits without the cardiovascular risk, choose DGL. If you use whole root, limit to 4 weeks and monitor BP and potassium.

6 commercial forms

Compare the main delivery options and what they’re best suited for.

Whole Chinese licorice root (gancao, sliced)

Traditional TCM

Dried Glycyrrhiza uralensis root, used in TCM formulas typically as a 'guide herb' alongside other botanicals. Contains 2–10% glycyrrhizin. Used in decoctions and prepared formulas — usually short-term and small per-day dose.

Whole-plant glycyrrhizin and flavonoid profile.

Standardized licorice root extract

Modern supplement form

Capsules and tablets standardized to glycyrrhizin content (e.g., 5–24% glycyrrhizin). Look for ≤100 mg glycyrrhizin per daily dose; limit course duration to ≤4 weeks.

Predictable glycyrrhizin dose; same pseudoaldosteronism risk.

Deglycyrrhizinated licorice (DGL)

Safer chronic option

Whole licorice extract with ≥97% of glycyrrhizin removed. Retains flavonoids (glabridin, liquiritin) for ulcer-protective and dyspeptic effects without the BP/potassium risks. Chewable tablets 20 min before meals.

Loses antiviral / anti-inflammatory glycyrrhizin effects, gains safety.

GutGard standardized extract

Dyspepsia trial form

Glycyrrhiza glabra extract standardized to flavonoids, tested in functional-dyspepsia RCTs at 75 mg twice daily. Glycyrrhizin content reduced to safe levels.

Trial-validated dose; reduced glycyrrhizin.

Topical licorice patches / oral mucosal patches

Aphthous ulcers

Adhesive intraoral patches containing glycyrrhiza extract for canker sores. Topical delivery means systemic glycyrrhizin exposure is minimal; the BP/potassium risks don't apply.

Local action; negligible systemic absorption.

Licorice tea / lozenge

Mild dose

Loose-leaf tea or throat lozenges. Glycyrrhizin content varies — a cup of strong tea can deliver 50–100 mg. Limit to occasional use; cumulative daily intake matters.

Per-cup dose modest but cumulative; track total intake.

Safety

Know the common side effects, key cautions, and who should avoid it.

Common side effects

fluid retention / mild edemaheadachelethargyelevated blood pressuremuscle weakness from low potassium

Serious risks

Who should avoid it

Pregnancy & breastfeeding

Avoid licorice during pregnancy. Heavy consumption (≈250 g/week of licorice) increases preterm-birth risk and has been linked to adverse neurodevelopmental outcomes in offspring (lower IQ, ADHD-like behavior in childhood follow-up of Finnish cohort). Even small amounts are not recommended during pregnancy or breastfeeding.

SourceNCCIH — Licorice Root: Usefulness and Safety

Bottom line: The risk profile is dose- and duration-dependent. DGL is the safer choice for chronic GI use; whole licorice should be limited to short courses and avoided entirely in vulnerable groups.

Interactions

loop diuretics (furosemide), thiazide diuretics (HCTZ)Major

Both glycyrrhizin and these diuretics deplete potassium. Combination increases risk of severe hypokalemia, arrhythmias, and digoxin toxicity if also taking digoxin.

SourceNCCIH — Licorice Root: Usefulness and Safety
digoxinMajor

Glycyrrhizin-induced hypokalemia sensitizes the heart to digoxin toxicity. Combination should be avoided.

SourceMemorial Sloan Kettering Cancer Center — About Herbs — Licorice
corticosteroids (prednisone, hydrocortisone)Moderate

Glycyrrhizin inhibits cortisol metabolism (via 11β-HSD2), potentiating corticosteroid effects and side effects. Lower steroid doses may be needed; monitor for steroid toxicity.

SourceMemorial Sloan Kettering Cancer Center — About Herbs — Licorice
hormonal contraceptives, hormone replacement therapyModerate

Glycyrrhizin may alter steroid hormone metabolism. Reports of breakthrough bleeding and altered contraceptive efficacy. Use a backup method if combining short-term.

SourceMemorial Sloan Kettering Cancer Center — About Herbs — Licorice
antihypertensives (ACEi, ARBs, BBs, CCBs)Moderate

Licorice raises BP via pseudoaldosteronism, antagonizing antihypertensive therapy. Avoid in anyone treated for hypertension.

SourceNCCIH — Licorice Root: Usefulness and Safety
warfarinModerate

Licorice can alter CYP-mediated warfarin metabolism. Monitor INR closely if adding or stopping.

Food sources

Licorice candy (real licorice, glycyrrhizin-containing)

Amount
1 oz (~75-200 mg glycyrrhizin — varies widely)
%DV
—

Anise-flavored 'licorice' candy (no real licorice)

Amount
1 oz (0 mg glycyrrhizin)
%DV
—

Licorice root tea

Amount
1 cup (~50–100 mg glycyrrhizin)
%DV
—

TCM herbal formula with gancao (typical)

Amount
1 dose (varies — 0.5–6 g dried root)
%DV
—

Choosing a product

What to look for on the label — and what to be skeptical of.

Look for…

DGL (deglycyrrhizinated) clearly labeled if you want to avoid the BP/potassium risks
Glycyrrhizin content stated on label for whole-root products — should be ≤100 mg per daily serving
Standardized extract (e.g., GutGard 75 mg) if you want a trial-tested product for dyspepsia
Single-ingredient product if you want to track effects and avoid hidden licorice in TCM blends
Third-party tested for purity (esp. heavy metals)

Be skeptical of…

'Adrenal support' — based on the cortisol-prolonging effect of glycyrrhizin, but causes pseudoaldosteronism in the process
Long-term immune-boost or antiviral claims — preclinical signal only; chronic use risks outweigh
'Detoxifies the liver' — no clinical evidence for systemic detox
Licorice candy as a 'health food' — many products have meaningful glycyrrhizin content and can cause hospitalization at heavy intake
Multi-herb adrenal stack with undisclosed licorice content (common in adaptogen blends) — can cause unexpected hypertension

Frequently asked questions

Will licorice raise my blood pressure?⌄

Whole licorice with glycyrrhizin can, especially with regular use. DGL does not.

Is Chinese licorice safer than European licorice?⌄

Both contain glycyrrhizin and share the same risks. DGL is the safer choice for chronic use.

References by claim

Post-intubation sore throat

NCCIH — Licorice Root: Usefulness and Safety (2024) link

Functional dyspepsia (with DGL)

Memorial Sloan Kettering Cancer Center — About Herbs — Licorice (2024) link

Safety

Yoshino et al., 2021 — PMC — Frontiers in Nutrition (2021) link

Aphthous ulcers (canker sores)

Martin et al., 2008 — General Dentistry (2008) link

Other references

Glycyrrhiza uralensis on Wikidata — Wikidata link

Track Chinese Licorice with Pilora

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Evidence-based·Last reviewed May 31, 2026·Evidence current as of May 31, 2026·How we grade evidence

Disclaimer: These statements have not been evaluated by the FDA. This page is educational, not a substitute for personalized medical advice. Evidence grades are AI-assisted assessments — talk to your doctor before starting any new supplement, especially if you’re pregnant, breastfeeding, on medications, or managing a chronic condition.